first basic model switching impl

[Snapex2409]

Added support for multiple micro models and mocked switching.
Multi-Model support via ModelAdaptivity class.
Switching currently hard coded as: upper half of all sims in the micro_sims list are set to use the second MicroSim type.

Checklist:

• I made sure that the CI passed before I ask for a review.
• I added a summary of the changes (compared to the last release) in the CHANGELOG.md.
• If necessary, I made changes to the documentation and/or added new content.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.

[IshaanDesai]

Good work already! I did a first pass, in which I looked at everything except the tests. I would like to do another review before we finalize things, especially to look at the model_adaptivity.py once more. Please take a look at my comments.

[IshaanDesai]

I am not sure about having macro locations as part of the switching function inputs. I could imagine the switching being solely based on the macro- and micro-scale data available at a particular point.

[Snapex2409]

I thought it might be useful to enforce FOM at certain locations, where the user can already expect high fluctuations in input/output or where maximal accuracy should be guaranteed.

[IshaanDesai]

I thought it might be useful to enforce FOM at certain locations, where the user can already expect high fluctuations in input/output or where maximal accuracy should be guaranteed.

Yes, that should be possible and required. But my comment was still about why the macro-scale coordinates need to be passed to the switching function. I look at the switching function as a function to be called individually at each location. If the switching mechanism requires a macro-scale location, it can be passed on a per-micro-scale simulation basis. I think having a single call-type switching mechanism is beneficial for the user.